Interaksi Antara Jumlah Nitrogen Dan Cara Panen pada Pertumbuhan dan Persentase Minyak Nilam yang Dihasilkan pada Panen Pertama

Patchouli oil is one of major components in perfumery industries as well as incense. Its smell is heavy and strong due to the presence of its major component called patchoulol or patchouli alcohol. However, the production has not stabilized yet because of several factors including cultivation. Experiment was conducted from November 1999-May 2000. Patchouli cuttings were grown in randomized complete block design with four replications. Nitrogen rates for this experiment were 0, 45, 90, and 135 kg ha-1 and three harvesting methods, which were three pairs of youngest leaves, 20 em from the tip and by leaving 20 em stubble from ground. Plant height and number of branches continued to increase significantly linear at higher N rates. There was significant interaction between N rate and harvesting method on wet and dry harvest mass. Effect of N on composite percentage differed for each harvesting method. The yield from three youngest leaves was higher than harvesting 20 em from the tip and leaving 20 em stubble from the ground for 45, 90, and 135 kg ha-1 respectively. Keywords: patchouli oil, nitrogen level, harvesting metho

Global synthesis of drought effects on cereal, legume, tuber and root crops production: A review

As a result of climate change, drought is predicted to pose greater pressure on food production system than in the past. At the same time, crop yield co-varies with both environmental (e.g., water, temperature, aridity) and agronomic variables (i.e., crop species, soil texture, phenological phase). To improve our quantitative understanding on the effects of these co-varying factors on agricultural productivity, we synthesized previous meta-analysis studies summarizing the results of numerous independent field experiments on drought and its effect on the production of cereal, legume, root and/or tuber (root/tuber) crops. We also included new crops species that were not covered in previous meta-analyses and the effects of heat stress. Our results indicated that cereals tended to be more drought resistant than legumes and root/tubers. Most crops were more sensitive to drought during their reproductive (i.e., grains filling, tuber initiation) than during their vegetative phase, except for wheat, which was also sensitive during vegetative phase. Recovery from drought impact at reproductive phase was either: (i) unfeasible for crops experiencing damage to their reproductive organs (e.g., maize, rice) or (ii) limited for root/tuber crops, provided that water was abundant during the subsequent root/tuber bulking period. Across soil texture, the variability of yield reduction for cereals was also lower in comparison to legume or root/tuber crops, probably due to the extensive and deep rooting system of cereal crops. As crop species, plant phenology, and soil texture were important co-varying factors in determining drought-induced crop yield reduction, no single approach would be sufficient to improve crop performance during drought. Consequently, a combination of approaches, particularly site-specific management practices that consider soil conditions (i.e., intercropping, mulching, and crop rotation) and selection of crop varieties adjusted to the local climate should be adopted in order to improve the sustainability of agricultural production in a changing climate

Ploughing and grazing alter the spatial patterning of surface soils in a shrub-encroached woodland

Author's manuscript made available in accordance with the publisher's policy.Grazing is known to affect the spatial patterning of soil resources through biologically-mediated processes such as the removal of plant biomass and deposition of dung. In dense shrublands, grazing is thought to reinforce the concentration of resources around shrubs (fertile island effect) by enhancing the movement of resources from the interspace to the shrub hummocks. Shrub removal practices such as ploughing, which is commonly used to manage dense shrub patches, has unknown impacts on the distribution of soil properties. In this study we examined the effects of two land management practices, grazing and ploughing, on the spatial distribution of surface soil resources. At the unploughed–ungrazed site, the connectivity (autocorrelation range) of shrub cover was about 3.9 m and there was a well-defined pattern in soil labile C that was related to the distribution of the cover of both shrubs and litter. We also observed a strong pattern of biological crust cover and an autocorrelation range of 2.5 m, similar to that of mineralisable and mineral N. At the unploughed–grazed site, the autocorrelation range of both shrub and crust cover was reduced to 1.9 m and 1.8 m, respectively, although the range of litter cover increased to 4.4 m. Under a treatment of grazing without ploughing, the autocorrelation range of soil labile C was less related to litter cover. Whilst ploughing slightly increased the autocorrelation range of both shrub and litter cover at sites that were grazed, it obliterated any spatial pattern in biological soil crusts. We attribute changes in the spatial patterns of soil N under grazing to inputs of animal dung rather than soil crust cover. Our results indicate that grazing alone, or in combination with ploughing, leads to reduced connectivity of shrub and crust cover, reduction in crust patterning, and marked effects on shrub–litter–nutrient spatial relationships. The results reinforce the notion that management of shrublands by grazing and ploughing is likely to have marked effects on the distribution of surface soils

Global synthesis of drought effects on food legume production

poster abstractFood legume crops play important roles in conservation farming systems, contribute to human nutrition and food security, yet in many regions of the world, their production has been adversely affected by drought. Currently, it remains unclear how the effects drought co-vary with legume species, soil texture, agroclimatic region, drought timing and intensity. To address these uncertainties, we collected literature data (1705 data points, averaged into 676 data points) between 1980 and 2014 that reported monoculture legume yield responses to drought under field conditions and analyzed this extensive data set using metaanalysis techniques. We performed unweighted analysis using the log response ratio (lnR) to calculate the bootstrapped confidence limits of those responses for each potential factor. Our results indicated that the amount of water reduction was positively related with yield reduction, but the extent of the impact varied with legume species and the phenological state during which drought occurred. Overall, field pea (Pisum sativum), groundnut (Arachis hypogea), and pigeon pea (Cajanus cajan) were found to experience lower yield reduction due to drought compared to legumes such as lablab beans (Dolichos lablab) or black grams (Vigna mungo). Although yield reduction was generally greater when legumes experienced drought during their reproductive stage compared to during their vegetative stage, legumes were sensitive to drought at all growth stages. Legumes planted in medium-textured soils also exhibited greater yield reduction compared to those planted in coarse- or fine-textured soils. In contrast, regions and their associated climatic factors were less associated with legume yield reduction. The study provides useful insights for legume agricultural planning and the direction of potential development of drought-resistant legume species to improve food security in the drought-prone regions of the world

Drought effects on root and tuber production: A meta-analysis

Roots and tubers such as potatoes and cassava rank within the top six among the world’s most important food crops, yet the extent to which their global production has been adversely affected by drought remains unclear. Greater uncertainties exist on how drought effects co-vary with: (1) root and tuber species, (2) soil texture, (3) agro-ecological region, and 4) drought timing. It is often assumed that potato is drought-sensitive whereas cassava and sweet potato are resistant to drought, but this assumption has not been quantitatively tested. To address these uncertainties, we collected literature data between 1980 and 2015 that reported monoculture root and tuber yield responses to drought under field conditions, and analyzed this large data set using meta-analysis technique. Our results showed that the amount of water reduction was positively related with yield reduction, but the extent of the impact varied with root or tuber species and the phenological phase during which drought occurred. In contrast to common assumptions regarding drought resistance of certain root and tuber crops, we found that yield reduction was similar between potato and species thought to be drought-resistant such as cassava and sweet potato. Here we suggest that drought-resistance in cassava and sweet potato could be more related to survival rather than yield. All root or tuber crops, however, experienced greater yield reduction when drought struck during the tuberization period compared to during their vegetative phase. The effect of soil texture on yield reduction was less obvious, and similarly we did not find any significant effects of region (and related climatic factors) on either yield reduction or drought sensitivity. Our study provides useful information that can inform agricultural planning, and influence the direction of research for improving the productivity and resilience of these under-utilized crops in the drought-prone regions of the world

Global synthesis of drought effects on cereal production

poster abstractAbstract Drought has been a major cause of agricultural disaster, yet how various factors (e.g., crop species, phenological phases) affect the vulnerability of cereal agriculture to drought remains unclear. Using a data synthesis approach, this study aims to better characterize the effects of these factors and to provide critical information on minimizing yield loss. We collected data from peer-reviewed publications between 1980 and 2015 which examined cereal yield responses to drought using field experiments. We performed unweighted analysis using the log response ratio to calculate the bootstrapped confidence limits of yield responses and calculated drought sensitivities for several key factors. Our results showed that yield reduction varied with species, with wheat having lower sensitivity to drought and yield reduction (20.6%) compared to maize (39.3%) at approximately 60% water reduction. Drought that occurred during the reproductive phase caused greater yield reduction (30%) than when it occurred during the vegetative phase (20%). While cereal cultivation in the drylands was more prone to yield loss than in the non-dryland regions, no difference was observed among sites of different soil texture. Informed by these results, we discuss possible causes and low-cost strategies that may minimize drought effect on crop yield

Can ridge-furrow plastic mulching replace irrigation in dryland wheat and maize cropping systems?

Dryland crop production requires significant water investments, but problems associated with irrigation have been observed in many dryland regions (e.g., China, Australia and the Mediterranean basin). A key strategy for maintaining crop yields without over-exploiting the scarce water resource is by increasing water use efficiency (WUE). Plastic mulching technology for wheat and maize has been commonly used in China, but their effect on yield, soil water content, evapotranspiration (ET), and WUE has not been compared with traditional irrigation. Using a meta-analysis approach, we quantitatively examined the efficacy of plastic mulching in comparison with traditional irrigation in the same region. By covering the ridges with plastic and channeling rainwater into a very narrow planting zone (furrow), our results showed that plastic mulching resulted in a yield increase comparable to irrigated crops but used 24% less water in comparison with irrigation due primarily to a much greater WUE and better retention of soil water. The higher WUE in plastic-mulched croplands was likely a result of a greater proportion of available water being used for transpiration (T) than evaporation (E). Currently production costs and residual plastic pollution hinder worldwide adoption of the technique, despite being a promising strategy for dryland cropping systems

Spatial patterns of infiltration vary with disturbance in a shrub-encroached woodland

Author's manuscript made available in accordance with the publisher's policy.Woody plant encroachment is known to have substantial effects on a range of ecosystem processes. Research worldwide indicates that the area around shrubs and trees has higher levels of infiltration than the interspaces. Little is known, however, about the hydrological consequences of shrub removal on infiltration, and how this might be influenced by grazing. We examined the spatial patterns of infiltration across three treatments relating to shrub removal and grazing: (i) undisturbed (ungrazed, unploughed), (ii) grazed but unploughed, and (iii) grazed and ploughed. In general we found that disturbance was associated with a greater cover of bare soil but lower infiltrability, our laboratory–based measure of infiltration. At the undisturbed site, bare soil was patchy and localized, with an autocorrelation range or connectivity of 1.4 m. The autocorrelation range of infiltrability at this site (A0 = 3 m) was larger than would be predicted from the size of the shrub canopy, and this was attributed to the presence of a well–developed understorey layer and biological soil crust community. At both grazed sites, infiltration was confined to the immediate canopy area of the remaining shrubs (A0 = 1.2 m in the unploughed–grazed site). Additionally, there was increasing connectivity of bare soil with disturbance, up to 6.8 m at the ploughed–grazed site. With increasing disturbance, resource-rich shrub patches are likely to become more developed, further reinforcing their growth and persistence at the expense of the bare interspaces. Our results indicate the importance of shrubs for maintaining landscape connectivity, and the long-term unsustainable practice of removal by ploughing, which is likely to promote shrub dominance rather than suppression

Meta-Analysis of Phosphorus Loss from No-Till Soils

Agriculture is a significant contributor to phosphorus (P) enrichment in aquatic ecosystems. No-till (NT) farming has been proposed as an alternative approach to conventional tillage (CT) in reducing soil P export, but published data have shown contrasting impacts, likely due to the interacting effects of different physical (climate region, rainfall variability, transport pathway, slope gradient) and management variables (NT duration, crop species). We conducted a meta-analysis to understand the extent to which each of these variables controls the concentration and load of different P fractions (dissolved P, particulate P) in agricultural runoff and leaching. In comparison with CT, particulate P loss was significantly lower with NT adoption (45 and 55% reduction in concentration and load, respectively), but an increase in dissolved P loss was observed. The extent of the reduction or increase, however, varied with different physical and management variables. In comparison with CT, for example, NT was not effective in reducing particulate P concentration during wet years and particulate P load on steep slopes (4–9%). Total P concentration was also similar with CT at sites under prolonged NT duration (∼10 yr) and at NT fields planted with soybean [Glycine max (L.) Merr.]. Our results underscore the need to consider the covarying physical and management factors when assessing the potential of NT farming in controlling P loss in the environment. The limited impact of NT on dissolved P loss remains a serious impediment toward harnessing the water quality benefits of this management practice

Impacts of no-tillage management on nitrate loss from corn, soybean and wheat cultivation: A meta-analysis

Although no-till (NT) has been promoted as an alternative land management practice to conventional tillage (CT), its impact on water quality, especially nitrate (NO3 −) loss remain controversial. We conducted a meta-analysis to compare NO3 − concentration and load in NT and CT systems via two major transport pathways: runoff and leaching. Rainfall variability, aridity, soil texture, tillage duration, crop species, and fertilizer type were used as co-varying factors. In comparison to CT, NT resulted in an overall increase of runoff NO3 − concentration, but similar runoff NO3 − load. In contrast, leachate NO3 − load was greater under NT than under CT, although leachate NO3 − concentration was similar under both tillage practices, indicating that the effect of NT on NO3 − load was largely determined by changes in water flux. Some deviations from these overall trends, however, were recorded with different co-varying variables. In comparison to CT, NT, for example, generated lower leachate NO3 − concentration and similar (instead of elevated) NO3 − leachate load from soybean fields (no N fertilizer applied). These results suggest NT needs to be complemented with other practices (e.g., cover crops, reduced N rate, split N application) in order to improve soil N retention and water quality benefits